“Like her father, right up until the end she was giving of herself, and proof of that is her organs are all being donated,” said Robert Egbert, a spokesman for the Port Authority Police Benevolent Association, referring to Caitlin Nelson, 21.

“She indicated throughout her life that she was an organ donor. Like her father, who gave everything he possibly could so others could live right up until the end, Caitlin just did the same thing,” Egbert said.

The Clark resident choked at the “Greek Life’’ dinner at her school, Sacred Heart University in Fairfield, Conn., on March 30, authorities said. She was rushed to the hospital but died Sunday.

Her father, James Nelson, worked for the Port Authority Police Department. He died in one of the World Trade Center towers helping to evacuate people on Sept. 11, 2001.

The family is now reeling with more “unimaginable’’ grief, a pal said.

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“I can’t even speak about what [Caitlin’s mom] Roseanne and her family are going through right now. It’s just unimaginable.”

Caitlin was 5 years old when her father died. She is survived by her mom and an older sister, Anne.

The PA source said he and James Nelson worked at the bus terminal together.

The source said he had recently heard a story about Caitlin at school.

“In one of her classes, they were given an assignment about Sept. 11, and they were randomly assigned partners to work with. Her assigned partner was another student who happened to be the son of a dad who worked and was killed that day,’’ the source said.

“This 9/11 theme continues to run through our lives,” the source said.

There were 37 Port Authority cops who died on 9/11, and “That was the largest single loss of any police department in the history of America,” he said.

“One of the things you have to keep in mind is that Sept. 11 doesn’t end for anyone who was involved in it. There’s nothing we can do about it. It will never end. It’s a part of your life. You accept it and you try to move on.”

“Unfortunately, it just continues.’’

Caitlin regularly volunteered to help children — driven by her own experience with tragedy.

She and her sister had worked at the Resiliency Center, which helps survivors of the Sandy Hook school massacre.